Quantum phases of hardcore bosons with long-range interactions on a square lattice
Quantum phases of hardcore bosons with long-range interactions on a square lattice
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DOI：
10.1103/physrevb.86.054516
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发表时间：
2012-06
影响因子：
3.7
通讯作者：
D. Yamamoto;Akiko Masaki;I. Danshita
中科院分区：
文献类型：
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作者：
D. Yamamoto;Akiko Masaki;I. Danshita
利用线性自旋波理论和集团平均场方法研究了正方晶格上具有长程相互作用的硬核玻色子的基态相图。具体地说，我们考虑两种类型的长程相互作用：一种只包括最近邻和次最近邻相互作用，另一种是偶极-偶极相互作用，其衰减与粒子间距离$r$为$\sim r^{-3}$。从量子Monte Carlo方法的分析可知，棋盘超固体（CSS）在前一种情况的基态相图中不存在，而在后者中存在。在前者中，我们发现，平均场解周围的量子涨落增强的棋盘和条纹固体订单之间的直接竞争，他们不稳定的CSS阶段。另一方面，在后一种情况下，CSS阶段的出现可以归因于没有与其他固体订单的竞争。我们还表明，集群平均场方法允许在一个精确的定量方式确定相边界时，考虑到相对于集群大小的缩放。结果表明，超流与固体（或CSS）之间的相变在粒子-空穴对称线附近为一级相变。
We study the ground-state phase diagrams of hardcore bosons with long-range interactions on a square lattice using the linear spin-wave theory and a cluster mean-field method. Specifically, we consider the two types of long-range interaction: One consists only of the nearest- and next-nearest-neighbor interactions, and the other is the dipole-dipole interaction that decays with the interparticle distance $r$ as $\sim r^{-3}$. It is known from previous analyses by quantum Monte Carlo methods that a checkerboard supersolid (CSS) is absent in the ground-state phase diagram of the former case while it is present in the latter. In the former, we find that quantum fluctuations around mean-field solutions are enhanced by the direct competition between the checkerboard and striped solid orders and that they destabilize the CSS phase. On the other hand, the emergence of the CSS phase in the latter case can be attributed to the absence of such a competition with other solid orders. We also show that the cluster mean-field method allows for the determination of phase boundaries in a precise quantitative manner when scaling with respect to the cluster size is taken into account. It is found that the phase transition between the superfluid and the solid (or CSS) is of the first order in the vicinity of the particle-hole symmetric line.